On my 2000 Kia Sportage the drain plug is on the bottom of the radiator. Look on the left side of the radiator(Bottom). It is a plastic wing nut. There is a drain hose about three inches long. The hose might help you find the plug.(wing nut)
Your local NAPA, Carquest or autoparts store should be able to show you a parts diagram for ordering exhaust pieces in a parts catalog. However this will only show you the original factory installation setup and not an aftermarket system.